The present invention relates to the field of separating and mixing operations including chemical processes and apparatus, more specifically, a process of separating gases by sorption.
Red mud is an insoluble waste generated during extraction of alumina (Al2O3) from mineral bauxite using the Bayer process. Red mud is an environmentally hazardous substance. Red mud is highly alkaline with a PH range of 10 to 13. The worldwide annual production of red mud is between 60 to 120 million tons. This figure increases annually. Red mud is further contaminated with metals and metal salts including, but not limited to, Fe2O3, Al2O3, SiO2, CaO, V2O5, Sc2O3, TiO2, and Na2O. Red mud also has a high concentration of NaOH. The proper disposal of red mud is estimated to represent 5% of the production costs of aluminum. Most of the aluminum refiners store the Red Mud sludge adjacent to the refinery, in open pit lagoons, to save money. Open pit storing of Red Mud sludges presents an immediate threat to the surrounding ecosystems.
Whenever feasible, the red mud is used as a construction material. Because the demand for red mud as a construction material is much less than the annual production, vast quantities of Red Mud only pile up in many countries of the world.
Clearly, a practical use for red mud would be of benefit to our society.